Year	Percent
1998-01-01	23.800
1999-01-01	21.150
2000-01-01	21.125
2001-01-01	19.425
2002-01-01	20.675
2003-01-01	21.425
2004-01-01	20.400
2005-01-01	19.775
2006-01-01	18.425
2007-01-01	16.450
2008-01-01	16.175
2009-01-01	21.000
2010-01-01	21.125
2011-01-01	19.750
2012-01-01	18.775
2013-01-01	19.550
2014-01-01	20.350
2015-01-01	22.025
2016-01-01	19.875
2017-01-01	19.800